Preheat your oven to 400°F.
Heat the olive oil in a 12-inch cast iron skillet over medium heat.
Add the onion, carrots, celery, and garlic. Cook for 6–7 minutes until softened.
Add the mushrooms and cook for about 10 minutes, stirring occasionally, until they've released their moisture and reduced in size.
Stir in the cooked brown lentils, peas, corn, rosemary, salt, pepper, and paprika.
Sprinkle the flour over everything and stir for about 1 minute.
Slowly pour in the vegan chicken broth and soy milk while stirring continuously.
Simmer for 5–10 minutes until the filling becomes thick, creamy, and similar to a chowder.
Remove from the heat.